Flaming Bottles: Doesn't Kill 'em

Flaming Bottles: Doesn't Kill 'em

Post by NURFBA » Wed, 25 Oct 1995 04:00:00



In reference to the practice of swabbing bottle necks with *** and
flaming them (for yeast culturing, etc.), I'm beginning to have serious
doubts about this method.   There was a thread on this topic in HBD a
while back.  Someone, I forget who, tried this method using a thermometer
and noticed the temperature didn't raise very much.  So, in a fit of
curiousity, I dipped a thermometer in *** and immediately flamed it.  
In several tries, the temperature never went past 120 degrees F.   I tried
it on a bottle neck and the surface temp was even lower, closer to 100
degrees F.   I suspect the evaporating *** is actually having a
cooling effect at the surface.   After this, I think I'm going to leave
the *** alone and let it do the job.  Any flames out there? (stupid
pun, couldn't resist!)

Davebrau  

 
 
 

Flaming Bottles: Doesn't Kill 'em

Post by Robert Curr » Wed, 25 Oct 1995 04:00:00


: In reference to the practice of swabbing bottle necks with *** and
: flaming them (for yeast culturing, etc.), I'm beginning to have serious
: doubts about this method.   There was a thread on this topic in HBD a
: while back.  Someone, I forget who, tried this method using a thermometer
: and noticed the temperature didn't raise very much.  So, in a fit of
: curiousity, I dipped a thermometer in *** and immediately flamed it.  
: In several tries, the temperature never went past 120 degrees F.   I tried
: it on a bottle neck and the surface temp was even lower, closer to 100
: degrees F.   I suspect the evaporating *** is actually having a
: cooling effect at the surface.   After this, I think I'm going to leave
: the *** alone and let it do the job.  Any flames out there? (stupid
: pun, couldn't resist!)

: Davebrau  

It's the *** vapor that burns, not the liquid, so there's little heat
transfer from the flame to the bottle.  If you're feeling brave or
foolish, you can pour a small amount of *** onto the palm of your hand
and light it, without getting burned.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

  "Ask a question and you are a fool for five minutes.  Do not ask, and you
   remain a fool forever."  - Ancient Chinese Proverb
              I do not speak for Air Products, and vice versa.

 
 
 

Flaming Bottles: Doesn't Kill 'em

Post by Pierre Jele » Wed, 25 Oct 1995 04:00:00


Quote:

> In reference to the practice of swabbing bottle necks with *** and
> flaming them (for yeast culturing, etc.), I'm beginning to have serious
> doubts about this method.   There was a thread on this topic in HBD a
> while back.  Someone, I forget who, tried this method using a thermometer
> and noticed the temperature didn't raise very much.  So, in a fit of
> curiousity, I dipped a thermometer in *** and immediately flamed it.  
> In several tries, the temperature never went past 120 degrees F.   I tried
> it on a bottle neck and the surface temp was even lower, closer to 100
> degrees F.   I suspect the evaporating *** is actually having a
> cooling effect at the surface.   After this, I think I'm going to leave
> the *** alone and let it do the job.  Any flames out there? (stupid
> pun, couldn't resist!)

You're right: "Flaming" does not mean soaking in *** and burning it
off. To properly flame an object for sterilization purposes, the object
must be dry, and it must be held/rotated in the flame for several seconds,
until its surface temperature reaches at least 300, preferably 400F.

*** does not kill healthy bugs terribly fast: it needs several
minutes of contact to do a decent, not thorough, job. The point of
burning off the *** from an object, typically a spreader, that has
been soaked in *** is just that: to burn off the ***. The fact
that the temperature does not rise is an advantage, as the spreader can
be used immediately without risking the health of the little critters.

Pierre
--
Pierre Jelenc                I like to have everything so good, I can

                                                            Calvin & Hobbes
http://www.FoundCollection.com/~pcj1/                              

 
 
 

Flaming Bottles: Doesn't Kill 'em

Post by David DeGra » Thu, 26 Oct 1995 04:00:00



Quote:

> It's the *** vapor that burns, not the liquid, so there's little heat
> transfer from the flame to the bottle.  If you're feeling brave or
> foolish, you can pour a small amount of *** onto the palm of your hand
> and light it, without getting burned.

A fun thing to try on a cold winter's night: Place raisins in a shallow
bowl, and soakthem in aprocot brandy, turn off the lights, and ignight
the raisins.
Grab 'em and eat 'em. Watch your finger be on fire. No pain at all.

On the other side of things, you can pour a *small* drop of liquid
nitrogen into your palm and watch it evaporate.  Just make shure it's
VERY SMALL.

David DeGraff

(sorry about the off topic post)

 
 
 

Flaming Bottles: Doesn't Kill 'em

Post by Tracy Aquil » Fri, 27 Oct 1995 04:00:00



Quote:

>> In reference to the practice of swabbing bottle necks with *** and
>> flaming them (for yeast culturing, etc.), I'm beginning to have serious
>> doubts about this method.
[snip]

>You're right: "Flaming" does not mean soaking in *** and burning it
>off. To properly flame an object for sterilization purposes, the object
>must be dry, and it must be held/rotated in the flame for several seconds,
>until its surface temperature reaches at least 300, preferably 400F.
[snip]

>Pierre

Based on many years of hands-on training, it's my understanding that when
doing microbiology, the purpose of flaming the mouth of a bottle, flask, or
tube is not to sterilize it, but rather to create a brief upward draft of
air which prevents airborne dust and other contaminants from settling into
the vessel. It normally isn't necessary to sterilize these objects as in
most cases they should already be sterile; if not, sterilizing after the
fact would be pointless (i.e. if the mouth of the bottle is contaminated,
the medium probably is also). When you flame the mouth of a vessel, do you
really wait for it to reach 400C? FWIW, I also use a lot of plastics these
days and most plastics can't take the heat.
    Tracy
 
 
 

Flaming Bottles: Doesn't Kill 'em

Post by Pat Babco » Sat, 28 Oct 1995 04:00:00




Quote:


>: In reference to the practice of swabbing bottle necks with *** and
>: flaming them (for yeast culturing, etc.), I'm beginning to have
serious
>: doubts about this method.   There was a thread on this topic in HBD a
>: while back.  Someone, I forget who, tried this method using a
thermometer
>: and noticed the temperature didn't raise very much.  So, in a fit of
>: curiousity, I dipped a thermometer in *** and immediately flamed
it.  
>: In several tries, the temperature never went past 120 degrees F.   I
tried
>: it on a bottle neck and the surface temp was even lower, closer to 100
>: degrees F.   I suspect the evaporating *** is actually having a
>: cooling effect at the surface.   After this, I think I'm going to
leave
>: the *** alone and let it do the job.  Any flames out there?
(stupid
>: pun, couldn't resist!)

>: Davebrau  

>It's the *** vapor that burns, not the liquid, so there's little
heat
>transfer from the flame to the bottle.  If you're feeling brave or
>foolish, you can pour a small amount of *** onto the palm of your
hand
>and light it, without getting burned.

I believe it to have been Timothy Laatsch who reported the trial. It is
referred to as 'wet flaming' and is most ineffective. A better method is
to flame the bottle neck and swab afterward as you feel necessary. Most
use the ethanol on the shoulders of the bottle, work area, and hands;
using only flame for the mouth of the bottle.

--
Pat Babcock                 | "Beer is my obsession, and I'm late for
President, Brew-Master      |  therapy..." -PGB
and Chief Taste-Tester      | "Let a good beer be the exclamation point
Drinkur Purdee pico Brewery |  at the end of your day as every sentence

SYSOP on The HomeBrew University - Motor City Campus BBS (313)397-9758
Visit the Homebrew Flea Market via http://www.FoundCollection.com/~pbabcock

 
 
 

Flaming Bottles: Doesn't Kill 'em

Post by Pierre Jele » Sat, 28 Oct 1995 04:00:00


Quote:

> Based on many years of hands-on training, it's my understanding that when
> doing microbiology, the purpose of flaming the mouth of a bottle, flask, or
> tube is not to sterilize it, but rather to create a brief upward draft of
> air which prevents airborne dust and other contaminants from settling into
> the vessel.

I've heard this explanation before, and frankly I don't believe it: If
anything, creating a draft would tend to cause dust to swirl up all over
the place. Furthermore, the object is flamed, then removed from the flame
for processing. You flame a pipet and a flask, remove them from the
flame, then stick the pipet into the flask or whatever, well away from
the flame.

             It normally isn't necessary to sterilize these objects as in

Quote:
> most cases they should already be sterile;

It is mostly to take care of little accidents: the finger touching the
pipet, the outside of the cap touching the lip of the flask, etc.

I hardly ever flame anything, and I don't get contaminations. I'm very
good ...  :-)

Quote:
>                              When you flame the mouth of a vessel, do you
> really wait for it to reach 400C? FWIW, I also use a lot of plastics these
> days and most plastics can't take the heat.

A correctly flamed pipet is hot; second-degree burn hot, sometimes! I know
from painful experience. And I also have lots of half-melted plastic
screw-caps!

All told, however, I agree that with today's disposable plastics, flaming
is mostly a thing of the past in laboratories.

Pierre
--
Pierre Jelenc                I like to have everything so good, I can

                                                            Calvin & Hobbes
http://www.columbia.edu/~pcj1/